Today, many trucks are used for cargo transportation in large, medium and small cities. However, the penetration rate of its industry is very low, and there are still a large number of food, meat, fruits, vegetables, drugs, alcohol, etc., which cause unnecessary losses due to deterioration in the transportation process every year. This is more indicative of the fact that there are A large development market, cold storage industry in this area also has a wide range of ways to expand. Set the thermostat to the required temperature and prechill the car for 1.5 hours to drain the heat remaining in the car; when loading, the refrigeration unit will be turned off and the cargo will be loaded quickly. When loading, the compartment must be pre-cooled or warmed up. Because the vehicle is parked in the open air, the temperature of the passenger compartment is usually the ambient temperature. If the temperature of the conveyed goods is not ambient temperature, the goods are loaded into the car, and the ambient temperature will affect the temperature of the goods being transported, resulting in a change in the quality of the goods being transported. Therefore, the car must be pre-cooled to the required temperature before loading. However, the refrigeration unit must be turned off at the time of loading (unloading). Many people do not shut down the refrigeration unit when loading or unloading goods. In fact, this is a very wrong operation. The reason is: When we precool the cabin, if it does not shut down, open the door of the car, because the fan of the evaporator of the refrigeration unit is working, the front of the fan is positive pressure, and the back is negative pressure, so the cold air from the upper part of the car Blow out, while the lower part will quickly inhale hot air from outside, resulting in a rapid rise in the temperature inside the compartment; if you load and unload cargo after the shutdown, because the fan is stopped, the air flow stops, the air pressure inside and outside the compartment is the same, which makes the external heat The speed at which air passes into the cabin is relatively slow. The goods must be pre-cooled to the required temperature, and the temperature of the goods checked at the time of loading; the refrigeration unit is used to maintain the temperature of the goods, not to reduce the temperature of the goods. Many users of refrigerated trucks have a wrong concept, and believe refrigeration units on refrigerated trucks loaded with goods are free to freezing within the passenger compartment or heated to a temperature they need. Therefore, the goods that are insufficient for the transport temperature are loaded into the carriage, and the refrigeration unit is set to its required transportation temperature, and the temperature of the cargo is lowered or raised to its desired temperature over a certain period of time. However, the opposite is true. Not only does the temperature fall (or does not go up), the cargo damages or deteriorates. Because the refrigeration unit of a refrigerated truck does not lower the temperature of the goods, but maintains the temperature of the goods, he packs the goods just like the quilts we used to sell cold drinks. When the external cold (heat) source passes radiation, conduction, and convection into the cabin, it is carried away by the cold air blown by the refrigeration unit and the heat source is cut off from the cargo. Therefore, at the time of loading, the temperature of the loaded goods must be measured first. If the set point temperature of the refrigeration unit is higher or lower than the cargo temperature, the temperature of the cargo in the compartment is difficult to reach the required temperature for transportation. The storage temperature and the transportation temperature of the goods must be the same. If the temperature of the goods changes frequently, the water will be lost, which will cause the quality of the goods to change, which will lead to a shortened shelf life of the goods. Even if the capacity of the unit exceeds the actual requirement, insufficient air circulation will be the main cause of the deterioration of the goods; any obstruction around the cargo may lead to “hot spotsâ€. A qualified refrigerated truck must ensure that there are good ventilation on the six sides of the carriage and there is no obstruction on the six sides of the cargo; good air circulation can ensure that the goods are transported under the proper temperature requirements. The cold (hot) gas blown by the refrigeration unit isolates the cold (hot) source that enters the compartment from the outside and protects the cargo. If a blockage occurs at one location, the cold (heat) source in this section will directly enter the item, causing the cargo temperature to change. Make sure that the return air shutter is in good condition; do not block the inlet of the evaporator (return air); insufficient return air will cause irregular circulation of the cold air and cause the top cargo to freeze. The goods must be stacked on double-sided pallets; the fresh-keeping pallets must not contain the picking film, and the film will block the circulation of cold air to the goods; the floor under the goods cannot be blocked. The general refrigerated truck floor uses vented aluminum rails; however, some refrigerated trucks do not have aluminum rails, and flat anti-skid floors are used. The non-slip floor is usually used as a third-party transportation company or a company transporter for dairy products. The purpose is to be suitable for the transportation of multiple products or to facilitate the cleaning of the ground. However, it must be noted that the loading must be done with double-sided pallets to ensure the circulation of cold air on the ground. It is forbidden to stack goods directly on a flat floor. Do not stack cargo in front of the evaporator outlet, as this will impede the cold airflow; obstruction above the cargo will cause a short circuit in the cold air flow. Maintain a minimum distance of 225 mm between the top of the cargo and the roof. When loading, do not stack the cargo too high. Make sure that the loading height is not higher than the level of the outlet. If the front of the air outlet is blocked by the goods or is too close to the goods, it will not only affect the storage and transportation temperature of the goods, but also affect the normal operation of the refrigeration unit. Because the air outlet is blocked by the cargo, the cold air (or hot air) cannot be circulated in the compartment normally, thus causing the local temperature of the cargo to rise. On the other hand, some defrosting designs for the refrigeration unit use air-induced defrosting. When the goods are too close to the air outlet, the coil in the evaporator of the unit will quickly frost (or ice), the air-sensitive switch will immediately operate, the unit will quickly enter the defrosting state; when the coil temperature rises to 9 degrees (design temperature) About, defrosting ends immediately. As a result, the above-mentioned operation of the unit will be reciprocated, resulting in a phenomenon in which the temperature in the passenger compartment does not fall. The intuitive feeling for everyone is that the unit is always defrosting frequently. In fact, it was caused by too much (more) cargo. The interior of the compartment must be kept clean; there should be no wrapping paper or paper scraps on the floor; debris can impede the flow of air or be inhaled by the evaporator. When using a refrigerated truck, the interior of the compartment should be kept clean. Due to the effect of the evaporator fan, air circulates in the compartment, causing ground shreds or dirt to be drawn into the evaporator fan. For a long time, a large amount of impurities will be sucked into the evaporator coil, affecting the cooling effect of the refrigeration unit. Because the coil is surrounded by a little bit of impurities, the heat exchange rate of the coil decreases. Therefore, after a few years of use, refrigerated trucks will feel that the cooling effect is worse than the beginning. Besides the cause of the malfunction, it is because the coils are too dirty. Therefore, ensuring the cleanliness of the ground in the carriage is the key to ensuring the normal operation of the refrigeration unit. When the door is opened, the freezer should be closed; the opening time of the door should be as short as possible; use bar-type curtains as much as possible when loading and unloading goods. Use partitions to separate dry goods (empty baskets) and perishable items. In order to ensure the temperature of the goods in the carriage, for the delivery vehicles in the city, it is recommended to use a strip curtain to ensure that when the cargo is unloaded rapidly (when the refrigeration unit is not closed), the cold air in the carriage will not be quickly lost. Different temperature goods are forbidden to be stored in the same compartment space. Should be separated by partitions. Because the freezer is used to maintain the temperature of the goods, not to cool down, mixing goods of different temperatures will affect the temperature of the goods and affect the quality of the goods. Correct operation and use of refrigerated trucks is the key to ensuring the quality of temperature-controlled goods. It also ensures that the refrigeration equipment can work properly. Single Rice Milling Machine,Rice Huller Machine,Rice Milling Equipment,Rice Mill Milling Machine HUNAN JINSONG MACHINERY CO., LTD , https://www.sheller.nl
September 23, 2019